We propose to organize a meeting focusing on biological and clinical aspects of T and B cell tumors. The four aims of the meeting will be to: (1) develop a more rational taxonomu of tumors which will be useful in diagnosis, prognosis and therapy; (2) understand the tumor-host relationship; (3) define the ability of tumor cells to differentiate and/or display normal behavior in vitro; and (4) discuss new therapeutic approaches to lymphoid tumors. The meeting will bring together immunologists, oncologists and transplanters to compare basic observations in animal models with clinical studies in humans.